ABSTRACT
The muscle-specific microRNA miR-206 has recently emerged as a potential regulator of genes involved in the formation and regeneration of the neuromuscular junction (NMJ). This study investigated miR-206-3p (miR-206) expression in synaptic and non-synaptic regions of denervated mice and α-dystrobrevin (Dtna)-knockout mice, as well as its impact on the formation and/or maintenance of agrin-induced acetylcholine receptor (AChR) clusters. In denervated, Dtna-deficient and crushed muscles, miR-206 expression significantly increased compared to what was seen for innervated muscles. Although miR-206 expression was slightly elevated in the synaptic regions of innervated muscles, it was dramatically increased in non-synaptic areas of denervated muscles. miR-206 targets transcripts of essential NMJ proteins, such as Dtna, α-syntrophin (Snta1) and rapsyn, but not the AChRα subunit (encoded by Chrna1) or Lrp4 in innervated muscles. However, in denervated muscles, AChRα transcripts, which increased significantly, become a target of miR-206. Co-expression of miR-206 with rapsyn, Dtna and Snta1 in C2C12 myoblasts significantly reduced their protein levels, and overexpression of miR-206 in myotubes disrupted agrin-induced AChR clustering. These results indicate that miR-206 fine-tunes NMJ signaling proteins by regulating transcripts of various proteins with different localizations under normal and pathological conditions.
Footnotes
Author contributions
Conceptualization: M.A.; Methodology: J.B., O.K., A.J.; Software: J.B.; Validation: J.B., O.K.; Formal analysis: J.B., O.K.; Investigation: M.A.; Resources: J.B., O.K., M.A.; Data curation: J.B., O.K.; Writing - original draft: M.A.; Writing - review & editing: M.A.; Visualization: M.A.; Supervision: M.A.; Project administration: M.A.; Funding acquisition: M.A.
Funding
This work was partially supported by the National Institute of Neurological Disorders and Stroke (R01NS111041) and the University of Michigan. Deposited in PMC for release after 12 months.
Data availability
All relevant data can be found within the article and its supplementary information.
